Stride will only record mileage when you tell it to! To record your mileage, you'll need to manually start recording your drive by clicking the green "+" button, and then "Track miles."
You can also add in a past drive by tapping on the same green "add" button on the home screen, selecting "Add Expense," and then clicking on "Add Miles Manually." To add a manual bulk entry, you can select the profile icon located in the upper left-hand corner of the home screen and then tap on the "Import Past Milage Log" option from the main menu.
Tip: There is a "Manage Drive Reminders" option when you select the "add" button. Tap on "+Add Reminder" to set a reminder.